Intervertebral discs, located between the endplates of adjacent vertebrae, stabilize the spine, distribute forces between the vertebrae and cushion the vertebral bodies. An intervertebral disc may deteriorate due to trauma, aging, or disease resulting in pain or discomfort to a patient. One common procedure for relief of patient discomfort is a disectomy, or surgical removal of all or part of the intervertebral disc. Often, this is followed by implantation of a device or spinal implant between the adjacent vertebrae in order to maintain or restore disc space height. Through stabilization of the vertebrae, the risk of reoccurrence of the same disabling back pain due to persistent inflammation and/or instability is reduced.
During implantation of a spinal implant, the endplates of adjacent vertebrae are sometimes milled to ensure firm implantation of the spinal implant by promoting bone ingrowth. One problem faced with typical milling instrumentation is that it is unable to form precise cavities at desired locations in the endplates. If not precisely prepared, the formed disc space may result in the expulsion of the implant, which can lead to injury of the patient.
Moreover, precise control of the milling equipment is required in order to avoid damaging vital tissues along the spinal column, such as nerves. During milling, the surgeon has to apply force to the milling equipment in order to counteract the forces created by the milling equipment cutting into the vertebrae. If not counteracted, the resultant force can cause the milling equipment to cut into portions of the vertebrae not intended to be milled.
Thus, there remains a need for implant endplate preparation tools that are capable of precisely defining cavities for securing implants.